[XRay][compiler-rt] Implement logging implementation registration

Summary:
This change allows for registration of multiple logging implementations
through a central mechanism in XRay, mapping an implementation to a
"mode". Modes are strings that are used as keys to determine which
implementation to install through a single API. This mechanism allows
users to choose which implementation to install either from the
environment variable 'XRAY_OPTIONS' with the `xray_mode=` flag, or
programmatically using the `__xray_select_mode(...)` function.

Here, we introduce two API functions for the XRay logging:

__xray_log_register_mode(Mode, Impl): Associates an XRayLogImpl to a
string Mode. We can only have one implementation associated with a given
Mode.

__xray_log_select_mode(Mode): Finds the associated Impl for Mode and
installs it as if by calling `__xray_set_log_impl(...)`.

Along with these changes, we also deprecate the xray_naive_log and
xray_fdr_log flags and encourage users to instead use the xray_mode
flag.

Reviewers: kpw, dblaikie, eizan, pelikan

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D40703

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@319759 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 59 insertions, 0 deletions

diff --git a/test/xray/TestCases/Linux/logging-modes.cc b/test/xray/TestCases/Linux/logging-modes.cc
new file mode 100644
index 000000000..22f6942b7
--- /dev/null
+++ b/test/xray/TestCases/Linux/logging-modes.cc
@@ -0,0 +1,59 @@
+// Check that we can install an implementation associated with a mode.
+//
+// RUN: %clangxx_xray -std=c++11 %s -o %t
+// RUN: %run %t | FileCheck %s
+//
+// UNSUPPORTED: target-is-mips64,target-is-mips64el
+
+#include "xray/xray_interface.h"
+#include "xray/xray_log_interface.h"
+#include <cassert>
+#include <cstdio>
+
+[[clang::xray_never_instrument]] void printing_handler(int32_t fid,
+                                                       XRayEntryType) {
+  thread_local volatile bool printing = false;
+  if (printing)
+    return;
+  printing = true;
+  std::printf("printing %d\n", fid);
+  printing = false;
+}
+
+[[clang::xray_never_instrument]] XRayLogInitStatus
+printing_init(size_t, size_t, void *, size_t) {
+  return XRayLogInitStatus::XRAY_LOG_INITIALIZED;
+}
+
+[[clang::xray_never_instrument]] XRayLogInitStatus printing_finalize() {
+  return XRayLogInitStatus::XRAY_LOG_FINALIZED;
+}
+
+[[clang::xray_never_instrument]] XRayLogFlushStatus printing_flush_log() {
+  return XRayLogFlushStatus::XRAY_LOG_FLUSHED;
+}
+
+[[clang::xray_always_instrument]] void callme() { std::printf("called me!\n"); }
+
+static bool unused = [] {
+  assert(__xray_log_register_mode("custom",
+                                  {printing_init, printing_finalize,
+                                   printing_handler, printing_flush_log}) ==
+         XRayLogRegisterStatus::XRAY_REGISTRATION_OK);
+  return true;
+}();
+
+int main(int argc, char **argv) {
+  assert(__xray_log_select_mode("custom") ==
+         XRayLogRegisterStatus::XRAY_REGISTRATION_OK);
+  assert(__xray_patch() == XRayPatchingStatus::SUCCESS);
+  assert(__xray_log_init(0, 0, nullptr, 0) ==
+         XRayLogInitStatus::XRAY_LOG_INITIALIZED);
+  // CHECK: printing {{.*}}
+  callme(); // CHECK: called me!
+  // CHECK: printing {{.*}}
+  assert(__xray_log_finalize() == XRayLogInitStatus::XRAY_LOG_FINALIZED);
+  assert(__xray_log_flushLog() == XRayLogFlushStatus::XRAY_LOG_FLUSHED);
+  assert(__xray_log_select_mode("not-found") ==
+         XRayLogRegisterStatus::XRAY_MODE_NOT_FOUND);
+}